1. Technical Field
This disclosure relates to ankle surgery and, more particularly, to a bone fixation plate, and a device for distal tibiofibular syndesmosis fixation.
Ankle injuries are among the most common of the bone and joint injuries. The ankle joint is formed of three bones coming together: the tibia which makes up the medial, or inside, anklebone; the fibula which parallels the tibia and makes up the lateral, or outside, anklebone; and the talus. The far ends of the tibia and fibula are known as the malleoli and together they form an arch that sits on top of the talus.
A fibrous membrane (the joint capsule) encases the joint architecture and is lined with a smoother layer called the synovium. The joint capsule contains the synovial fluid produced by the synovium. The synovial fluid allows for smooth movement of the joint surfaces. The ankle joint is stabilized by three groups of ligaments, which are fibers that hold these bones in place.
Surgery to repair an ankle fracture is indicated for patients who suffer a displaced ankle fracture involving the bone on the inside of the ankle (tibia), the bone on the outside of the ankle (fibula), or both. As the fibula is much narrower than the tibia at the ankle joint, a fracture of the fibula is much more frequent than a fracture of the tibia. One injury that may occur in the ankle is a disruption of the distal tibiofibular syndesmosis. A syndesmotic injury is a disruption of the strong fibrous ligaments that hold the fibula and tibia together near the ankle joint. If the syndesmosis is disrupted, then the ankle joint will be unstable and surgery is usually indicated.
The distal tibiofibular syndesmosis is usually described as being comprised of four ligaments. These ligaments are the anterior inferior tibiofibular ligament (AITFL), the posterior inferior tibiofibular ligament (PITFL), the transverse ligament (TL), and the interosseous ligament (IL). The primary role of these ligaments is to act as tensile members that stabilize the fibula within the distal tibiofibular joint. Injury to these ligaments, either isolated or concomitant with fractures of one or both the tibia and fibula, results in diastasis of the ankle joint which manifests as ankle instability.
As used herein, the term “syndesmosis” is intended to mean an articulation of bones, in particular those portions of the tibia and fibula forming the ankle, in which the bones are joined by means of a ligament. Thereby, the distal tibiofibular syndesmosis is a syndesmotic joint formed by two bones and four ligaments. The distal tibia and fibula form the osseous part of the syndesmosis and are linked by the above mentioned anterior inferior tibiofibular ligament (AITFL), the posterior inferior tibiofibular ligament (PITFL), the transverse ligament (TL), and the interosseous ligament (IL). Although the syndesmosis is a joint, in the literature the term syndesmotic injury is used to describe injury of the syndesmotic ligaments. Sometimes the transverse ligament (TL) is also called inferior transverse ligament of the tibiofibular syndesmosis. As the transverse ligament (TL) lies in front of the posterior inferior tibiofibular ligament (PITFL) and is very close to the latter, for purposes of reconstruction, these two ligaments can be regarded as a single ligament. Therefore, although there are four ligaments in the distal tibiofibular syndesmosis, if this disclosure mentions three ligaments of the distal tibiofibular syndesmosis, it is understood that the transverse ligament (TL) and the posterior inferior tibiofibular ligament (PITFL) are counted as a single ligament.
2. Description of Relevant Art
US 2015/0051601 A1 relates to an apparatus and method for syndesmosis fixation. It shows an assembly including two pieces. The first piece is an oblong bone plate and the second piece is a small bone plate placed on top of the bone plate. Three sutures are fixed on the one end at the small bone plate and on the other end in the tibia, with one suture penetrating the fibula.